Control Button's are normally linked to a cell and so that cell changes when the button is Pressed True or not Pressed False
You can also link the button to some VBA code which will activate when pressed
To overwrite or place a value in a cell it is as simple as
[pre]
Code:
Sub Button_Pressed()
Worksheets("My sheet").Range("A1").value = 1234
' or
' Worksheets("My sheet").Range("A1").value = my formula
End Sub
I agree regarding "Cells(LastRow + 1, "A")", I've never seen that, and I'd sweared it didn't work... just until five minutes ago when I downloaded ganeshm's file and run macro with F8 (the second time when I didn't believe it worked the first time and it didn't raise any error).